1. Field of the Invention
The present invention relates to a process and an apparatus for stocking semifinished products for manufacturing tyres for vehicle wheels.
Preferably, the object of the invention is an apparatus and a process for stocking semifinished products consisting of drawn or extruded profiles intended to form semifinished products, preferably tread bands of tyres for trucks.
2. Description of the Related Art
A tyre for vehicle wheels generally comprises a carcass structure including at least one carcass ply having respectively opposite end flaps in engagement with respective annular anchoring structures, integrated into the regions usually identified as “beads”, which have an inner diameter substantially corresponding to a so-called “fitting diameter” of the tyre on a respective mounting rim.
Associated with the carcass structure is a belt structure comprising one or more belt layers, located in radial superposed relationship with each other and with the carcass ply and having textile or metallic reinforcing cords with a crossed orientation and/or substantially parallel to the circumferential extension direction of the tyre. A tread band is applied to the belt structure at a radially external position, which tread band too is made of elastomeric material like other semifinished products constituting the tyre.
The tread band is manufactured through drawing. The drawing gives rise to a semifinished product defined by a band or belt having a preset cross-section profile, which belt is devoid of the tread pattern and is cut to size on the basis of the dimensions of the tyre to be made.
To the side surfaces of the carcass structure, which each extend from one of the side edges of the tread band to the respective annular structure anchoring to the beads, respective sidewalls in elastomeric material are applied in an axially external position, which sidewalls can also be previously manufactured as drawn or extruded profiles.
After the drawn or extruded semifinished products have been manufactured, the semifinished products that are, for example, intended to form the tread band or the sidewalls of a tyre, are conveyed on a roller conveyor and loaded on suitable book trucks, where they remain stocked until they are deposited on the carcass.
In order to move the semifinished products from the conveyor to the book truck, using two operators to grasp each semifinished product by the ends, lift each semifinished product manually and deposit each semifinished product on the book truck is known.
Subsequently to building of the green tyre carried out through assembly of the respective semifinished products, moulding and vulcanisation treatment is generally carried out that aims to cause structural stabilisation of the tyre through cross-linking of the elastomeric compositions and also to imprint a desired tread pattern on the tread band wound around the carcass before vulcanisation and to imprint possible distinctive graphic marks at the sidewalls.
Automatic devices for loading materials onto benches are further known.
For example, document U.S. Pat. No. 4,029,222 discloses an apparatus for loading material in sheets onto a plurality of trays of a book truck. The apparatus comprises a loading mechanism located near the book truck, to load a preset number of sheets of material onto the trays of the book truck. A wait mechanism is arranged near an end of the loading mechanism far from the book truck, to transport the sheets on the loading mechanism when the loading mechanism is devoid of sheets and to retain the sheets when the loading mechanism is provided with sheets. An alignment mechanism is arranged near an end of the wait mechanism far from the loading mechanism to align the sheets and convey them to the wait mechanism.
Document U.S. Pat. No. 3,866,774 discloses a method and apparatus for automatically stocking tyre tread bands. The tread bands that advance in sequence along a first conveyor are supplied to a rotating removal drum where they are lifted onto a second conveyor. Rotating arms are arranged on the second conveyor, which arms project the band through the space onto the trays of a book truck. The book truck includes an indexing unit that indexes each of the trays in a horizontal position at which the indexing unit receives a band. Means is provided for progressively varying the trajectories of the launched bands in such a way as to ensure that the bands are deposited on the respective tray in undeformed condition.
Document JP2008122 discloses a chain conveyor that is movable around a fulcrum, consisting of a shaft, and able to be retracted between the rollers of a roller conveyor to convey a tread band. When the band has reached a preset position, the chain conveyor is lifted and the tread band is lifted therewith. A sliding table is brought near the shaft, the chain conveyor is driven and the band is conveyed on a loading conveyor placed on the table. The table is moved in such a way that an end of the loading conveyor moves to an end of a bench. The table is returned to the shaft whilst the loading conveyor is driven and the band is transferred automatically. The Applicant has addressed the problem of improving the manufacturing process for manufacturing tyres, in particular in relation to the management of semifinished products that are manufactured and stocked before being applied to the tyre.